This paper presents a comparison of the radio landscape and radio advertising in European countries. The commercial radio landscape in Europe varies considerably from country to country, ranging from Sweden where there is no commercial radio to Italy where there are around 2,5 commercial stations. In many countries, broadcasting is dominated by the state-run national networks and stations (eg. Austria, Switzerland, UK), others have a highly de-regulated set-up without the co-ordination of networks (eg. Italy, Finland). Radio advertising expenditure depends on many factors, most obviously the reach and audience size of commercial radio. Regulations play a large part in many countries and can make the medium inflexible. In some countries governments have ruled against the formation of networks by local stations, thereby making it difficult to provide the mass market penetration which is attractive to large advertisers. The paper looks at these and other factors, covering types and numbers of stations, audience reach, commercial stations' share of radio audience, average time of listening, the distribution of total advertising expenditure on national and local advertising, and media cost level for commercial time. A systematic comparison of these factors between countries is presented. Based on this, radio advertising expenditure in Denmark is forecasted, and its relationship to coverage demonstrated. Conclusions are presented on how these factors determine the radio advertising potential and radio share of total adspend.